Device for producing modulated currents



Dec. 8, 1931. M. L. ALMQUIST DEVICE FOR PRODUCING MODULATED CURRENTS Filed May l5, 1930 lmemm's- Zst Set INVENTOR Mlumyaas ATTORNEY Patented Dec. 8, 1931 s UNITED-f STATES PATENT OFF-WE *i MIL'roN L. nrurraurs'r,` or BROOKLYN, NEW YORK, `nssreNon 'To' Mantener rHoNn AND TELEGKAPK ooMrANY, Vn CoRroRATroN or NEW YORK nnvrcn non PRODUCING MODULATED GURRENTS application. mea l may 15,

.- This .invention relates generally to signaling systems More. particularly tlns invert tion rela-tes to arrangements for producing i modulated. currents. Still more particularly thisinvention relates to apparatusjemploylng aicolumn 4otair and a vibratory element for producing modulated currents. i a

In conneetionwithtelephone systems, there '1 has recently arisen aneed for means .wheref 1o by a. `lineman may 4transmit 4 ringing current7 i.` ei, currentof a frequency of,l for example, .1000. cycleainterrupted or modulated' by a` current otfa; frequency pf, for example, 20.

cycles?7 over. a circuitequipped4 with appaia tus sultableto handlefsuch currents.. Inl or`` available for. producing thefnecessary modulation. One of thediiliculties Vinvolved 1s 1 der that thifsgmaybe done, `it `is necessary thatla lsource `oi current of, for example,

y 1000i]gcycles.` aswell as another source .of

'i' currentof, forfexample, 20 cycles, be readily thatsuch equipment inust beflight in weight and small insiZe sothat it-.m'ay ,be readily` carried from place-to placealongwithpthe telephone linemans familiar. test -set.. ,The

latter test set :involves about as mueh'weiglit asv itis practical? fora Alinemanto carry.` It is also important` that -such equipment be L quite inexpensive. y

30 i' In order that these diiiicultiesfmay be overcome, itis-proposed in this invention to devise a .whistle or pitch pipewhich shall pro-` duce the necessary 100G-cycle note modulatediat theQO-cycle rate. Inasmuchas the pres-V ent Vlineman@ `'test `set is equipped with atelephone transmitter7 this can be used to receive the modulated tone `produced by the whistle or pitch pipeand to apply currentcorrespondingto this tone to atelephone `line. .Such a whistleor pitch pipe will olif.

viousl small in. Siae .its weiolitne liv'ible a, n i 'o i 7 It is the ngeneral"object 'thisiinvention to "devise a readily portable device :forA pro-k ducrng modulated currents suitabletor ringing `purposes in connectionwith telephone lines. i u

Other rand furthei'fY objects of l this iinvene 1930. Serial N0. 452,651;`

when read in connection with the accompany-` ingdrawings, in which Figure l` shows an openv wire pair or telephone. line7 a test- "set,I

and a whistle or `pitch pipe designed' togive a toneA simulating rlnglng currents; Fig.` 2

shows means forV adjustably mountingl a` whistle or pitchpipe with respect to thetelevL phone transmitter; Fig. 3 .showsv one form Referring to Fig. l of the drawings, an

. open wire pair or telephone'line is designated` i L.` 11A telephone linemans test' set may be coni nected tolineL jbymeans of aipairof .test-'r1- elips designated K1 'and'Ka The test set in j chicles the familiarforms Vof transmitter T v andMreceiverrfR, a condenser C, windingsW 1g.

and W2. and a battery B@ The whistle-or pitch pipel is designated Rand this maybe' placed infront of the transmitteratany dis` tance therefrom and displaced att-any fpre-V determined angle so that its 'tonetwill .be

suitably impressed `uphonthe diaphragm of the transmitter. The-whistle or pitchfpipe will be..clescribed in greater detail herein-fV after in connection with Figs. 3.4 and 5Y of the drawings. l. VThe whistle or pitch pipe P will produce:

modulated waves simulating telephone ring-A ing current, and these willbe impressedupon the diaphragm of the transmitter T. The

currentof battery B will be corresponding ly modulated and transmitted to line L by` .virtue of theinductive propertiesof Windings W1 and "WTV The circuit extending toY the line L will include clip K1. 'eondenserC7 i windingsNVl and VQ, receiver R, and clip K2.'

Fig. 2 shows the lineman-s test box in which is mounted, among other things, 'the transmitter T. The deviceP'is arranged sothati i `it may -beseparated fromthe 'ytransmitter." T by any predetermined `distance anddis-z` placed angularly with respect 'tofthis transmitter by any predetermined amount.' 'Here a U-shaped member designated U is mountf` l ed onthe outerfsurtace ofthe linemanstest box7 and thisjmember supportsa-metallic plate E through which a hole is bored to accommodate a screwthreaded member F which meshes with a screwthreaded Wing i nut G. The device P is mounted on another metallic plate J and may be moved angularly With respect "to the transmitter T about 3 an axis K. The member J maybe grooved` in order Athat the whistle 4or pitch pipe P .maybe readilyV spaced from the transmitter i the desired tone 1000er/cles." reedv S, tuned to about Q0*` T at any predetermined distance. Thus, by loosening the Wing nut G, the pipe P` may be `slid to or` from `the transmitter T by any amount and thenut G may be fastened to `the screw-threaded member F in `order to maintain the spacing constant. It will be apparent that by revolving;r the pipe P to some predetermined angular displacement with respect to the tra1`1smitterT,lthe mod-` ulated tone produced thereby may be direct- 1y impressed upon `the diaphragm of the transmitter T. f

Fig. 3` 'shows one 'form of embodiment of the `Whistle or pitch pipe P Varranged to'give `Here a# chamber H in= cludes a column of air of such length lasto be resonant ata frequencyof, for example,

cycles,*is supported by' thebaseD of the arrangement. :Theoreed S supports a ,vfme"` V atiitsfree end and this vane is adjacent to the openingof thepipe from which soundf 735 isemitted.` Byblowing through the mouthvpiece M, the columnlof air .Within the chami will brought into resonance, and*V itwill produce a"l000cycl e`note. `The reed" S will 'be set into mechanical vibration at a` 20cycl`e rate `and thiswill modulate the 1000+ f `cyeletiorleAsoasto simulate oneform of tele-l phonejringirng current.

4 vand represent another form vof` embodxment of awhistle or pitchpipe suit-A able to `carry `out the* .principles of the iny ventom` ",Here there are "two chambers H5y andY H2, both oflwhich include columns of air, but theseL aref' resonant at two different frequencies. The column of air Withinthe v*chamberH1 is of smallerlength than that Within chamber and, therefore, the reso-L4 nant frequency offthe Vcolumn Within cham*- berH1 will higher thantha't of` the Col-` umn Within chamber H2. These chambers and H2 may be se't sofas to,produce"col-` nipruletied for `the Vpurpose of controlling the umnsu resonant at frequencies dififeringfrom each other bythe frequency offmodulation desired.; `for example, the respective i fre- Mquencieis `may be 1020 and J1000`cycles, 1000 tmd980 cycles, '1010 andl990 cycles, `andfso on.

Pistons N, and"Ngare'adjustably posi.- tioned in chambers H1; and'H-Q, respectively. screwmhtenrde'd members 'Yy and Y- `ajre'supported by! th'ev D, and thesefmay be `Inapositions ofthe pistons `Nif and N2, respectively. i By causing the pistons to be moved inwardly so fas to decrease the'lengths of the `col'nil'rnis ofair ihk-the chambers H1` and Ilz',

the resonant frequencies of'these columns will be increased, and as these pistons are Vmoved outwardly, the columns of air will` `have lower resonant frequencies.

While this invention has been shown in certain particular embodiments merely for the purpose of illustration, it will be under-` stood 4that the principlesxof this invention may beapplied to other andwidely varied organizations Without departing` from `the Aspirit of tlieinvention scope of the appended claims.

What is claimed is:` Y l. The method of producing a doubly-modulated aircurrent of definite frequency characteristics with a column of air and ame-V chanically vibrating -element `of elongated.

shape fixed at one end "and free atthe other, which consists in simultaneouslyresonating said column of air at a predetermined "fre-V` quency and mechanicallyvibrating` the free"` end of said element ata diil'erengrpredeterfg' mined frequency.

2. Apparatus for producingiimodiilated,

currents, comprising a chambersup orting ia column of Vair having a'resonant fof `'I'Jredetermined value, one-end :o Said chamber beingopemand a tuned reed "having" a natural' vibratory, frequency Vof adifferentY and predetermined i value,` `issie* reed being mounted-'Within `said Achamber andixed yin,

position-at the closedlendof saidchamber.,

uency L f 3. The combination of a` chamber :closedY x at one end' and .open at `the other,ysaidfc`ham-` bernhaving an effective length corresponding to a predeterminedfrequency, ayreed tuned` to a different` predeterminedfrequency one` md @which is' .fixedin positionauhe 'closed end of said cha,mber,fand a vane attache d, tot

end ofjsaid chamber.

the free-endof said "reedfadjacent to theopen 4. A device for simultaneously'producing1 air currents of twofrequencies of prefleterl` mined values comprising two chambers `of uniform cross-sectional'area and of equal length, two pistons each located within ione of said chambers, and screw-threaded means for controlling);` the relative positions `of said pistons Within said chambers.

5. Apparatus forprodu`cing` -modillated ririlgging currents,V comprising a chamber sup.` ,porting a column of a1r havinga resonant.'

frequency ,ofl predetermined value,` said` ringing currents. f

. 6. Apparatus for :producing double.. L

quency ringing `currents comprisingwo 1,30

chambers; of the same length each. enclosing l f comprising two chambers of unlform crosssectional area and of equal length, two plsa column of air, means associated with each chamber for adjusting its effective length so as to change the resonant frequency "of the enclosed air column to any desired value, means for simultaneously resonating both of said air columns, and means for converting `the resultant air currents into ringing currents.

7. A device for simultaneously producing Y air currents of two predetermined frequencies tons, one mounted in each chamber, and means associated witheach chamber for adjusting the positionof the enclosed piston. A

`In testimony whereof, I have signed my name to this specicaton this 14th day of May, 1930.

MILTON L. ALMQUI ST. 

